Nirsevimab may curb RSV severity - Report - MDSpire
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Nirsevimab may curb RSV severity

Real-world estimates showed protection across emergency, inpatient, and intensive care settings during Canada’s first universal immunization season.

  • By

  • Andrea Surnit

  • September 18, 2026

  • 3 min

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Clinical Report: Nirsevimab may curb RSV severity

Overview

Nirsevimab demonstrates effectiveness against RSV-related hospitalizations among infants during the first season of universal immunization in Canada, with an overall effectiveness of 78%.

Background

Respiratory syncytial virus (RSV) is a leading cause of bronchiolitis and pneumonia in infants, significantly impacting healthcare resources. Effective prevention strategies are crucial in reducing RSV-related morbidity and mortality in this vulnerable population.

Data Highlights

Care SettingEffectiveness (%)
Overall78
Emergency Department Visits77
Inpatient Hospitalization79
ICU Admission97

Key Findings

  • Overall nirsevimab effectiveness against laboratory-confirmed RSV was 78%.
  • Effectiveness was 77% against emergency department visits and 79% against inpatient hospitalization.
  • Effectiveness was 97% against ICU admissions.
  • Estimated effectiveness was 90% among infants born prematurely.
  • Effectiveness decreased over time: 85% at 7-29 days, 69% at 30-59 days, and 78% at 60-89 days post-administration.

Clinical Implications

Clinicians should consider the timing and administration of nirsevimab as part of RSV prevention strategies.

Conclusion

Nirsevimab shows effectiveness in reducing RSV-related hospitalizations among infants.

Related Resources & Content

  1. Buchan SA, et al., JAMA Network Open, 2025 -- Nirsevimab may curb RSV severity
  2. MDSpire News, 2025 -- Nirsevimab Shows 83% Efficacy Over 6 Months
  3. MDSpire News, 2025 -- Nirsevimab Linked to Lower Infant Hospitalization Risk Than Maternal Vaccine
  4. American Academy of Pediatrics, 2025 -- Recommendations for the Prevention of Respiratory Syncytial Virus Disease in Infants and Children
  5. JAMA Network Open — Nirsevimab and a Community Recall-Based Immunization Strategy for Child Bronchiolitis Prevention
  6. JAMA Pediatrics — Nirsevimab Immunization to Prevent Pediatric RSV Hospitalizations
  7. CDC -- Respiratory Syncytial Virus (RSV) Vaccine Safety
  8. Recommendations for the Prevention of Respiratory Syncytial Virus Disease in Infants and Children: Policy Statement | Pediatrics | American Academy of Pediatrics
  9. Respiratory Syncytial Virus–Related Hospitalizations Among Infants Receiving Nirsevimab | Public Health | JAMA Network Open | JAMA Network

Original Source(s)

Nirsevimab may curb RSV severity

  • by Andrea Surnit

  • September 18, 2026

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